MedWire News: Long-term exposure to ozone is associated with an increased risk of death from respiratory causes, researchers have found.\n\nA two-pollutant model in the study, published in the New England Journal of Medicine, showed that levels of fine particulate matter less than 2.5 µm in diameter (PM2.5) were associated with death from cardiovascular causes, whereas increased ozone concentrations were associated with an increased risk of death from cardiopulmonary causes.